Pros:

sensible image quality on the edge of the frame in the 12–16 mm range,

slight longitudinal chromatic aberration,

low lateral chromatic aberration,

silent and very fast autofocus.

Verdict from Lenstips, ” you deal here with a fast, ultra wide angle zoom instrument closed in a solid, weather-resistant casing, very difficult to design and produce. It is able to provide sensational image quality in the frame centre…If the producer adds just a piece of cloth instead of a solid case to a lens costing almost $2000 it’s really an exaggeration ”